This invention relates, in general, to semiconductor device processing, and more particularly to a vacuum wafer transport and processing system and method.
The processing of semiconductor wafers to fabricate devices and integrated circuits requires numerous steps in various types of reactors and process chambers. The wafers being processed are commonly moved from chamber to chamber manually. The manual transportation of the wafers subjects them to particulates and other impurities. The particulates and other impurities result in increased defect density and lower quality devices.
Cluster tools such as the Applied Materials Model 5000 are capable of performing multiple process steps without breaking vacuum. This greatly reduces the exposure of wafers to the atmosphere as well as manual wafer handling. A typical cluster tool includes a central transport module to which multiple process modules are coupled. The transport module includes a single robotic arm which transports wafers between the transport module and the various process modules. When a wafer has been transported into a specific process module, the process module is sealed from the transport module and processing takes place therein. The vacuum pressure of the process module may be the same or different than the vacuum pressure of the transport module depending upon the specific processing step.
Cluster tools are severely limited by their design, namely the presence of only a single robotic arm to transport wafers between the transport module and various process modules. First, since all wafer transport is dependent upon a single robotic arm, throughput is restricted. Second, the entire operation of the cluster tool is entirely dependent upon the robotic arm. If the arm malfunctions, the entire system becomes inoperative until the arm is repaired.
Accordingly, it would be highly desirable to have a vacuum wafer transport and processing system that would allow for higher throughout and not be dependent upon a single robotic arm.